United Nations Secretary-General Ban Ki-moon has urged world leaders to act in concert to ensure that a legally binding treaty is reached next year.

The political agreement was struck in Copenhagen, Denmark, on Saturday morning after negotiations had come to a standstill, with Ban intervening at the last minute to assuage nations which felt they had been excluded from parts of the negotiations.

The accord includes an agreement to working towards curbing global temperature rise to below 2 degrees Celsius, efforts to reduce or limit emissions, and pledges to mobilize $100 billion a year for developing countries to combat climate change.

The leaders were united in purpose, but they were not united in action. "While I am satisfied that we sealed a deal, I am aware that the outcome of the Copenhagen conference, including the Copenhagen Accord, did not go as far as many have hoped," Ban said on Monday.

The two-week-long United Nations conference, attended by 128 heads of State and government, was marked by interruptions in negotiations due to divisions between States over transparency and other issues.

"The leaders were united in purpose, but they were not united in action," Ban pointed out.

Nonetheless, he said that the talks "represent a beginning - an essential beginning," because without nations hammering out a deal in Copenhagen, the financial and technical support for poorer nations agreed upon would not take immediate effect.

The coming challenge for the UN will be to harness political will and translate it into action, said the Secretary-General, who will set up a high-level panel on development and climate change.

Due to the complexity of the negotiations and the entrenched positions held by many countries, "everybody knew that it would not be an easy task," he said, emphasizing the importance of taking proactive action to clinch a legally binding pact next year instead of dwelling on the Copenhagen talks.